hi guys ... i want to write a program to convert a hexadecimal number to a decimal number using c++ ... can anyone help me in writing that program?

help me please

Please post your relevant code. If you do not know how the conversion is done, read that first. Google is your friend.

This post has been edited by Louisda16th: 29 Nov, 2007 - 06:44 AM

i want to write a program to convert binary , octan or hexadecimal number to decimal ... i wrote it if its binary or octal and it was easy because its just numbers but in hexadecimal i have to work with numbers and letters which mean i have to use string ... and the main problem with the string how can i deal with each digit if its a string ? its easy if its number to get each digit alone by using mod and division ... but if they are letters i cant divide or use the mod ...

here is my work :

#include<iostream>
#include<cmath>
#include<string>
using namespace std;
int main()

{
int base,num,numC=0,counterC=0;

cout<<"please enter the base of the number you want to convert : ";
cin>>base;
cout<<endl;

switch(base)
{

case 2:

cout<<"Enter a number in the binary base : ";
cin>>num;

while(num>0)
{

switch(num%10)
{

case 0: numC+=0;
case 1:numC+=pow(base,counterC);

}

num=num/10;
counterC++;
}

cout<<"The number in the decimal is : "<<numC<<endl<<endl;

break;

case 8:

cout<<"Enter a number in the octal base : ";
cin>>num;

while(num>0)
{

switch(num%10)
{

case 0:numC+=0;
case 1:numC+=pow(base,counterC);
case 2:numC+=2*pow(base,counterC);
case 3:numC+=3*pow(base,counterC);
case 4:numC+=4*pow(base,counterC);
case 5:numC+=5*pow(base,counterC);
case 6:numC+=6*pow(base,counterC);
case 7:numC+=7*pow(base,counterC);

}

num=num/10;
counterC++;

}

cout<<"The number in the decimal is : "<<numC<<endl<<endl;

break;

case 16:

cout<<"Enter a number in the hexadecimal base : ";
cin>>num;

switch(num)
{
case 0:numC+=0;
case 1:numC+=pow(base,counterC);
case 2:numC+=2*pow(base,counterC);
case 3:numC+=3*pow(base,counterC);
case 4:numC+=4*pow(base,counterC);
case 5:numC+=5*pow(base,counterC);
case 6:numC+=6*pow(base,counterC);
case 7:numC+=7*pow(base,counterC);
case 8:numC+=8*pow(base,counterC);
case 9:numC+=9*pow(base,counterC);
case 'A':case 'a':numC+=10*pow(base,counterC);
case 'B':case 'b':numC+=11*pow(base,counterC);
case 'C':case 'c':numC+=12*pow(base,counterC);
case 'D':case 'd':numC+=13*pow(base,counterC);
case 'E':case 'e':numC+=14*pow(base,counterC);
case 'F':case 'f':numC+=15*pow(base,counterC);
}

break;


default:
cout<<"sorry invalid base"<<endl<<endl;

}

return 0;
}


its too long maybe its possible to write it shorter but you know i am just a beginner in the programming world ...

Store the input in a string. Extract each digit one by one. when you get to letters, just store their equivalent numbers:

Hope this helps.

yeah thats the idea ... but the problem is how to get each digit individually ?

for example : 2A

how can i get the A without the 2 ? and if i got it then i can switch the A with 10 ... as u said !

guys ?!

I'm not sure if you're doing this as part of an assignment, or just as a challenge, but there's an extremely short, simple way of doing this in C++.


stringstreams are like FIFO string buffers. They work much in the same way as cin and cout (except to a memory buffer rather than a standard I/O device). you can add strings/numbers/etc using the << operator, and retrieve things with the >> operator.

Thanks alot Bench ... believe me i am just trying to do it as a challenge ...
in fact i dont get what you really mean ... you know i am just a beginner :$ !

in M.excel there are functions called left and right ...

for example :
4rty

left("the cell name " ; 2 )
which will give me : 4r

right("the cell name " ; 1)
which will give me : y

arent there the same functions in c++ ?!

This post has been edited by RauLiTo: 29 Nov, 2007 - 11:15 PM

You can think of Strings as an array of chars. So if the user has enetered an argument and you have stored it as a string then the string will have a length and you will be able to use a for loop to run through the string taking the each letter at a time:



would produce "h".

Hope that helps!

Foo

This post has been edited by foohoo: 30 Nov, 2007 - 02:38 AM

thaaaaaaaaanks alot mr foofoo
thats exactly what i am looking for ... i wrote my program and everything fine now thanks all of you